1. Field of the Invention
Embodiments described herein include methods and systems of embedding and decoding three-dimensional watermarks in stereoscopic images.
2. Description of the Related Art
FIG. 1a illustrates a conventional stereoscopic conjugate pair of images. Two images illustrated therein represent the right 101 and left 103 images for a viewer. A viewer wearing a special set of glasses such as the glasses with red-green filters would perceive a 3D image. It should be noted, however, that the red-green filters are included herein only as an example, and other known mechanisms can be employed such as linearly and/or spherically polarized glasses as used within the Real 3D Cinema or Disney Digital 3D systems. Known 3D technologies are described in detail, such as, “3D Standards”, Matt Cowan, Chief Scientific Officer, REAL 3D, Chairman, DC28-40 Stereoscopic Digital Cinema, and “REAL D 3D Theatrical System—A Technical Overview”, Matt Cowan, Chief Scientific Officer, REAL 3D, both of which are incorporated by reference herein in their entirety.
Although only one set of images is represented, many 3D scenes can be collected together and made into a movie. Such a 3D movie that has been digitized will be referred to as three dimensional (3D) video. Example featured movies include “Journey to the Center of the Earth,” and future feature movies include Pixar offerings to include the Toy Story and Cars series. More descriptions of three dimensional movies can be found in “RealD Deal Will Bring 3D To Small Theater Screens”, Sarah McBride, Wall Street Journal, Sep. 2, 2008. “Behind the Scenes of a Next Gen 3D Film,” Cohan Andersen, PC Magazine, Jun. 18, 2008, and “Disney unveils animation slate,” Ben Fritz, Dade Hayes, Variety Magazine, Apr. 8, 2008, all of which are incorporated by reference herein in their entirety.
It should be noted that a 3D effect in 3D images is achieved by shifting pixels in the horizontal direction, along the viewer's eye direction (i.e., x-parallax) to create the illusion of depth in the image scenes. That is, some parts of the 3D image appearing nearer to the viewer while some other parts of the images appearing farther from the viewer. The fused effect creates a perceived 3D depth. This perceived depth is characterized by a depth map 107 shown in FIG. 1b, in which lighter colored portions represent those that appear closer to the viewer compared with darker colored portions. More detailed description of depth map is provided in U.S. Pat. No. 6,215,898, which is incorporated herein its entirety.
FIG. 2 illustrates example watermarks that can be encoded into 3D images. In conventional watermarking methods, watermarks, such as shown in FIG. 2, are encoded into lower bits of color information of 3D images. Although these conventional methods handle 3D object watermarking, these methods' primary focus on the primitive level (e.g. vertices, surfaces) where an object model (e.g. 3D wireframe model) is assumed prior to 3D transmission. The illustrated examples show a watermark 201 created by adjusting three dimensional mesh, and another watermark 203 created by adjusting textures associated with three dimensional model. For such conventional methods, the encoded object's model is necessary in order to decode the watermark.